Ruben Loftus-Cheek has been widely praised by Chelsea fans after shining as a makeshift centre-back in the side's 3-2 win against Luton on Wednesday.
The Blues were looking to book their place in the quarter-finals of the competition, but they got off to the worst possible start when Reece Burke put Luton ahead inside two minutes.
Thomas Tuchel's side hit back through Saul Niguez, yet they went into the break behind as Harry Cornick restored Luton's lead in the 40th minute.
It appeared that Chelsea were in real danger of being knocked out by their Championship opponents, but second half goals from Timo Werner and Romelu Lukaku got the job done and ensured that the west London outfit are now just one game away from another trip to Wembley.